Logically, the straightforward form of the sentence would be
Environmental considerations and Australia’s absorptive capacity are conspicuously absent, as the investment infrastructure required to provide services to the growing population is.
But when you have a very long subject (the investment infrastructure required to provide services to the growing population) and a short verb phrase (is) in a subordinate clause, it can be difficult for the hearer or reader to parse, and English allows you to swap them: this process is called extraposition, and gives you the original sentence
Environmental considerations and Australia’s absorptive capacity are conspicuously absent, as is the investment infrastructure required to provide services to the growing population.
When the subject itself has an embedded relative clause, it is also possible to extrapose only that clause. So if the subject were the fuller the investment infrastructure that is required to provide services to the growing population, you could extrapose that relative clause:
Environmental considerations and Australia’s absorptive capacity are conspicuously absent, as the investment infrastructure is that is required to provide services to the growing population.
In principle, you can do this even with the "reduced relative clause" required to provide services to the growing population, but as others have pointed out, the result (your second sentence) has another, more obvious, reading with a different structure. But in speech, and with a comma after "is", I can imagine somebody saying your second sentence.
I agree with others that this "as is" has become a set phrase, but I think in this case it is completely analysable and doesn't have a special meaning.